Oracle计算datafile可以resize收缩的空间

Jun 3, 2015 | Oracle

有时数据库服务器磁盘空间在不知不觉中已经不够用了，当数据库无法使用报错时，需要紧急恢复，再进行转移或磁盘扩容，这时可以临时释放一定磁盘空间，保障数据库正常运行

计算datafile可以resize收缩的空间.

col name for a40
col resizecmd for a80
select a.file#,a.name,a.bytes/1024/1024 CurrentMB,
       ceil(HWM * a.block_size)/1024/1024 ResizeTo,
       (a.bytes - HWM * a.block_size)/1024/1024 ReleaseMB,
       'alter database datafile '''||a.name||''' resize '||
       ceil(HWM * a.block_size/1024/1024) || 'M;' ResizeCMD
from v$datafile a,
     (select file_id,max(block_id+blocks-1) HWM
       from dba_extents
       group by file_id) b
where a.file# = b.file_id(+)
and (a.bytes - HWM *block_size)>0
order by 5

如果只是想对某个表个间的datafile resize,可采用:

select a.file#,a.name,a.bytes/1024/1024 CurrentMB,
       ceil(HWM * a.block_size)/1024/1024 ResizeTo,
       (a.bytes - HWM * a.block_size)/1024/1024 ReleaseMB,
       'alter database datafile '''||a.name||''' resize '||
       ceil(HWM * a.block_size/1024/1024) || 'M;' ResizeCMD
from v$datafile a,
     (select file_id,max(block_id+blocks-1) HWM
       from dba_extents where file_id in 
              (select b.file#  From v$tablespace a ,v$datafile b
                where a.ts#=b.ts# and a.name='MP2000')
       group by file_id) b
where a.file# = b.file_id(+)
and (a.bytes - HWM *block_size)>0
order by 5

计划tempfile可以resize的空间.on apply that have only one tempfile

select 'alter database tempfile '''||a.name ||''' reize '||b.siz||'M;' from v$tempfile a,
     (select tmsize.maxblk*bk.value/1024/1024 siz from
         (select nvl(max(segblk#),128) maxblk  from v$sort_usage) tmsize,
         (select value From v$parameter where name = 'db_block_size') bk) b

Oracle